Inland waterways of the United States

The inland waterways of the United States include more than 25,000 mi (40,000 km) of navigable waters. Much of the commercially important waterways of the United States consist of the Mississippi River System—the Mississippi River and connecting waterways.

The Columbia River is the only river on the West Coast (and arguably the entire North American Pacific coast) that is navigable for a significant length. The river is regularly dredged and freight barges may reach as far inland as Lewiston, Idaho through a system of locks; however, there are strict draft restrictions beyond the confluence with the Willamette River. The Sacramento and San Joaquin Rivers, the Snake River, and the Umpqua River are examples of other West Coast rivers that are dredged for navigation. The steep grades and variable flows of most other West Coast rivers make them unsuitable for large boat travel. Also, most large rivers there are dammed, often in multiple places, to supply water for hydroelectricity production and other uses. Mountainous terrain, and a shortage of water, make canals in the West unfeasible as well.

Most navigable rivers and canals in the United States are in the eastern half of the country, where the terrain is flatter and the climate is wetter. The Mississippi River System, including the Gulf Intracoastal Waterway (GIWW) connects Gulf Coast ports, such as Mobile, New Orleans, Baton Rouge, Houston, and Corpus Christi, with major inland ports, including Memphis, Kansas City, St. Louis, Chicago, St. Paul, Cincinnati, and Pittsburgh. The Lower Mississippi River from Baton Rouge to the Gulf of Mexico allows ocean shipping to connect with the barge traffic, thereby making this segment vital to both the domestic and foreign trade of the United States. The Mississippi River System is connected to the Illinois Waterway, which continues to the Great Lakes Waterway and then to the Saint Lawrence Seaway. Many other eastern rivers are navigable as well, including the Potomac, the Hudson, and the Atchafalaya Rivers, which are all dredged by the Army Corps of Engineers.

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